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Thread: Cool Down Period

  1. #1
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    Default Cool Down Period

    Hi, Not really and "advanced" technical question, but do you guys reccomend a cool down period for diodes generally ?

    For example, if I run my DPSS 532nm Green 1200mw for 8hrs continuously, how long do you think I should let my diode cool down for after ive stopped the modulation ?

    I normally leave the fans running (case / diode /psu) for about 15mins to ensure the TEC's remove the all the heat from the diode / crystal is this neccessary ?

    Had a fair bit of experience with the old water cooled argon lasers (coherent hilight / purelight etc etc) which obviousley needed the cool down period

    Im guessing the answer to my question is yes, just intrigued to know what others do

  2. #2
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    Personally I don't believe the diodes need any cool down, and TEC cooling might do if the heat exhaust side is hot, but even then it should only be a minute or two at most. If you feel more comfortable with 10-15 minutes then all well and good, it can't hurt.

    Personally, I only worry about the warm up time for my DPSS. Sometimes I wish I could drop the shutter while running the 532 just to keep it warm and ready to go. Most of the time it's not an issue for beam shows though. Graphics is another thing.
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    Quote Originally Posted by dnar View Post
    Personally, I only worry about the warm up time for my DPSS. Sometimes I wish I could drop the shutter while running the 532 just to keep it warm and ready to go. Most of the time it's not an issue for beam shows though. Graphics is another thing.
    I also see some problems when running the DPSS green...
    At 19gr Celcius roomtemp the laser takes forever to get at operating temp and stop modehopping.
    I am still planning my RGB projector build, but i am thinking of putting in some form of regulated heating inside the projector (at te upper table/optical level)

  4. #4
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    Quote Originally Posted by liteworx View Post
    Hi, Not really and "advanced" technical question, but do you guys reccomend a cool down period for diodes generally ?

    For example, if I run my DPSS 532nm Green 1200mw for 8hrs continuously, how long do you think I should let my diode cool down for after ive stopped the modulation ?

    I normally leave the fans running (case / diode /psu) for about 15mins to ensure the TEC's remove the all the heat from the diode / crystal is this neccessary ?

    Had a fair bit of experience with the old water cooled argon lasers (coherent hilight / purelight etc etc) which obviousley needed the cool down period

    Im guessing the answer to my question is yes, just intrigued to know what others do
    I think this is a great question. I have always wondered the same thing. I do have a few projectors with Green DPSS and some passively cooled 445nm so due to that I usually try to let the fans run for at least 5 minutes or so. I think 15 min may be overkill but can not hurt.
    Larry

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    Default

    thanks for the replies guys, will probably carry on with a 10min cool down period, but handy to know when im in a rush to get out of a gig in the future !

    anthony could you not implement a galvo blanking system like what used to be used with gas tubes ? or is that kind of blanking too innefficent / expensive

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    Quote Originally Posted by liteworx View Post
    thanks for the replies guys, will probably carry on with a 10min cool down period, but handy to know when im in a rush to get out of a gig in the future !

    anthony could you not implement a galvo blanking system like what used to be used with gas tubes ? or is that kind of blanking too innefficent / expensive
    I do want a shutter/blanking servo in the projector for safety reasons.
    I haven't done alot of research yet, but i am planning a +3Watt build and i really doubt that a shutterflag is happy being toasted with +3Watts for 15min.
    Maybe a system that involves a shutter and a lens?

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    Just use a mirror on the shutter that takes the beam on to your base plate. that way it does not have all that heat build up.
    Larry

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    why would you have the beams on your shutter for 15 minutes? if you're in a cool down cycle, you want the lasers to be off and the fans blowing.

    Quote Originally Posted by Anthony View Post
    I do want a shutter/blanking servo in the projector for safety reasons.
    I haven't done alot of research yet, but i am planning a +3Watt build and i really doubt that a shutterflag is happy being toasted with +3Watts for 15min.
    Maybe a system that involves a shutter and a lens?
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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    Quote Originally Posted by swamidog View Post
    why would you have the beams on your shutter for 15 minutes? if you're in a cool down cycle, you want the lasers to be off and the fans blowing.
    Swami,

    Please read the entire topic.
    My reaction was on DNAR about the WARMUP time

  10. #10
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    Do you need the lasers on to warm up though?

    On mine if its sat in idle they warm up anyway.

    At start up I have a pinky beam for a minute or so if I turn the output on. However, let it idle a few mins with no output and instantly I get white and it modulates better. Maybe it has heating as well as cooling, don't know but I don't seem to need output to warm up.

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